August kottmann



,v 1,633,256 June A. KOTTMANN 7 7 KEY MECHANISM FUR CALCULATING AND ADDING MACHINES Filed May 12, 1925 jrenfii' tier-ways Patented June 21, 1927.

UNITED STATES PATENT" OFFICE.

AUGUST KOTTMANN, F SOMMERDA, GERMANY, ASSIGNOR TO THE FIRM: RHEINISCHE METALLWAABEN- MASCEINENFABRIK, OF DUSSELDORF-DERENDOBF, GER- MANY Application tiled May 12, 1925, Serial No.

The key-mechanisms, for calculating and adding-machines are commonly so .con-

structed that abutments of various kinds, directly actuated by the keys, are brought into the path of the racks. These. keymechanisms have the drawback that each stop must be machined individually, rendering the cost of manufacture very considerable, and a replacement of parts, due to damage to the key-mechanisms is difficult.

The object of my invention is to avoid these drawbacks and to provide a key-mechanism for calculating and adding-machines which is simple in construction, and whereby a ready exchange of the individual elements in the event of damage may be efi'ected.

This is achieved by providing the lower. end of the keys with toothed wheels of uniform shape, each toothed Wheel being provided with a finger projecting laterally of the wheel, and positioned thereon in accordance with the value of its corresponding key, and by the provision of a device, for each toothed whee'hfor locking it in its initial position, and of a stop for limiting the rotation of the wheel.

An embodiment of the invention is illustrated, by way of example, in the accompanying drawings, in wh1ch:

Fig. 1 is an elevation partly 1n section, 'of key-mechanism according to the invention.

Fig. 2 shows two of the keys in elevation,

' one of them'bein depressed, and

Fig. 3 is a side elevation of one of the keys with its toothed wheel.

In the frame 1 of the machine the keys 2 are guided in usual manner in a coverplate' 3 and a bar 4 situated below, Around each key 2 is a compression spring 5, arranged between a stop on the key, under the cover plate 3, and the guide bar 4. Each key 2 carries at its lower end a toothed wheel 6, all the wheels being of uniform shape and freely rotatable. Each of said Wheels is provided with a separate finger 7, projecting laterally of the wheelsurface,

as may clearly be seen from Figs. 2 and 3. The finger 7 may be secured to the toothed wheel, or the latter may be provided with one extended toothprojecting beyond its surface. A stop 8, in thaform of a pin, is provided on each key 2 1n the KEY MECHANISM FOR CALCULATING ADDING MACHINES.

29,673, and in Switzerland March 20, 1925.

path of its finger 7, by means of which the rotary movement of the toothed wheel is limited. In order to always secure the toothed wheels in their initial position, so that they may correctly enga e in the rack dunn the depression of the e provision is made on the guide bar 4 of Ice ng devices 9 which, for example, may be pins adapted to engage between the teeth in order to hold the toothed wheel 6 in the desired position. Such a pin could be substituted, for example, by a spring-pawl or other suitable device.

The operation of the key-mechanism according to the invention is as follows The toothed wheels 6 are set in accordance with the value of their correspondmg keys. v

If, for example, as shown in Fig. 2 the key for the numeral 6 is depressed, the corresponding toothed wheel 6. is brought into engagement with the rack 10, and by the subsequent movement of said rack, the Wheel 6 is rotated until the finger 7 strikes against the stop 8, whereby, in the given example, since the key for the numeral 6 is to be-considered, the wheel 6 is advanced to the extent of six teeth From this moment onward the rack 10 can be moved no further, but remains stationary until the device for returning all the racks into their initial positions forces the racks in the op posite direction and thus returns them to their initial positions. the calculation operations and during the cancellation, the keys 2 are moved upwards under the action of the springs 5, whereupon the locking devices 9, provided on the bar 4:, engage in the corresponding spaces of the teeth of the toothed wheels 6, and lock them in their initial positions, so that they are in the correct position for the next stage of operation.

I claim:

After completion of 1. An actuating mechanism forcalculating machines, comprising, in combination, a e an operating member, a gear carried by said key forenga'gement at will with said operating member to be rotated there by, and a projection on said gear located thereon in accordance with the value of said 'key and cooperating with said key to limit the rotation of said gear.

2. An actuating for calculatby said key I being ini machines, comprisin in combination, a ey, an operating mem r, a. gearv carried for engagement at will with said operating member to be rotated thereb a finger on said gear projecting; laterafiy from the surface thereof, sai finger located on said gear in accordance the value of said key, anda stop located on 'the key and cooperating with said to limit the rotation of said 10 gear.

In testimony whereof I have afiixed my signature.

v AUGUST KOTTMANN. 

